Dear Dongsoo,

firstly it's easy to calculate from (200), if you simply multiply the dhkl of (002) by 2 you will get the lattice parameter. Calculation of lattice parameter of solid solution and gamma prime is not obvious using standard XRD due to very small difference of their lattice parameters so peak deconvolution may be needed.

What is more, nickel based superalloys usually are in form of single crystals so I would turn mechanically few chips of alloy and mill it in mortar. Afterwards you should get nice XRD reflections from powder. For calculation of lattice parameter use as many peaks as possible, so perform scan in full 2theta range. Remember that gamma prime will give you more peaks for instance (100) peak which will tell you exactly lattice parameter.

Thanks for answer.

Can I ask to you something?

After chipping your ingot, how was the size of powder? and is it irregular shape?

Also, what is different with quality of XRD in powder and ingot?

Thanks a lot.

After chipping you may obtain chips in range of 0.1 mm. The best powder size is about 0,05 mm because its size is comparable with the penetration depth of Cu radiation (which is used in most cases). But in my opinion 0.1 will be still far better than ingot. If you perform XRD from large grained or single crystal ingot you may obtain only one peak. From my experience in Ni based alloys grain size after casting into the metal chill was in range of 1 mm (slower cooling -> larger grains). You can see grains in figure 3b in attached publication.

To obtain good XRD results you should get diffraction from many grains that's why powder is best solution.

Article Microstructure of cast Ni-Cr-Al-C alloy

 Thanks for answer.

You mean, because the accurate lattice parameter calculation can be come from intensity and number of planes in XRD, we should get a lot of exact and high intensity of lattice planes. But, in case of as cast or as solution heat treated samples, because they have large grain size, lattice plane is very limited in XRD. Thereby, in order to make many grains, powder is best solution. Is it right?

If so, in here, I have one more question.

Even though the sample has large size of grain, because the crystallographic orientation of grain will be not changed during making as powder, diffracted plane may be same I think with powder. Is it wrong?

The exact idea of making powder is to obtain many peaks in XRD what will be caused by random crystalographic orientation of powder particles. If you will do XRD from single crystal you will get one peak and only if you are lucky it will be (002).

My alloy is polycrystalline alloy fabricated by conventional casting (Investment casting). So, the peaks have been detected randomly whenever analyze the XRD (strong peak is different whenever doing).

So, now, I am doing the XRD with solution heat treated sample to minimize the effect of randomly orientated grain.

But, except for (111)peak, the intensities of other peaks were substantially low. Thereby, not exact calculation of lattice parameter has been conducted.

If so, which kinds of ball materials have been used for milling after chipping?

Your alloy is polycrystalline but as you said only (111) peak is intensive so you have large grains and/or orientation of grains is near to (111) due to solidification texture. I used zirconia ball and zirconia chamber. If you make fine chips short milling will be enough.

Could I ask to you something?

When you analyzed the XRD with just as cast sample,

were their XRD data same (strong peak position)?

In my case, even though same sample was used, peak was different. I think it is due to a lot of grain boundaries and solidification textures, but if so, is it impossible to analyze the XRD with as cast sample?

Hello Everyone

This subject is also my question. I have single crystal superalloy and I have done XRD and the highest intensity peak is for 002. But I do not know how to calculate the misfit between Gamma and Gamma Prime, The de-convolution method is said for this reason, Do you have any references or experience regarding this?

Thank you

Another possibility is electrochemical extraction from the alloy:

DOI:j.msea.2010.07.036